Direct digital signal processor control of multi-channel scan for re-establishing connections in a wirelessly networked device

ABSTRACT

A method and system for establishing a wireless connection between a portable computer system and a wireless network, particularly when the portable computer system goes out of coverage and a wireless connection needs to be re-established. The portable computer system has a main processor and a digital signal processor (DSP). The main processor is placed in a low power mode, conserving battery power. When the portable computer system goes out of coverage, broadcast channels used by the wireless network are scanned by the DSP instead of the main processor to identify channels that have sufficient signal strength for the wireless connection. Thus, the main processor remains in the low power mode. When the DSP identifies acceptable channels, it wakes up the main processor and identifies the channels having sufficient signal strength. The main processor then establishes a wireless connection using one of the channels identified by the DSP.

This Application is a Continuation Application of the co-pending,commonly-owned U.S. patent application with Ser. No. 11/114,271, filedApr. 25, 2005, by C. Skinner et al., and entitled “Control ofMulti-Channel Scan for Re-establishing Connections in a WirelesslyNetworked Device;” which in turn is a Continuation Application of U.S.Pat. No. 6,901,276, Ser. No. 09/847,768, filed May 1, 2001, by C.Skinner et al., and entitled “Direct Digital Signal Processor Control ofMulti-Channel Scan for Re-establishing Connections in a WirelesslyNetworked Device;” both of which are hereby incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of portable computer systems,such as personal digital assistants or palmtop computer systems.Specifically, the present invention relates to a portable computersystem with wireless (radio) communication capability.

2. Related Art

A portable computer system, such as a personal digital assistant (PDA)or palmtop, is a computer that is small enough to be held in the hand ofa user and is thus “palm-sized.” By virtue of their size, portablecomputer systems are lightweight and so are exceptionally portable andconvenient.

Portable computer systems are generally powered using eitherrechargeable or disposable batteries. Because of the desire to reducethe size and weight of the portable computer system to the extentpractical, smaller batteries are used. Thus, power conservation inportable computer systems is an important consideration in order toreduce the frequency at which the batteries either need to be rechargedor replaced. Consequently, the portable computer system is placed into alow power mode (e.g., a sleep mode or deep sleep mode) when it is notactively performing a particular function or operation.

Some portable computer systems are equipped with radio transmitters andreceivers (transceivers) that provide the capability for two-waycommunication between the portable computer system and a wirelesscommunications network. Accordingly, in addition to the main processor,the portable computer system may include a digital signal processor(DSP) for processing data to be transmitted or data that are receivedvia the transceiver.

In the past, when communication occurred between the portable computersystem and the wireless network, the portable computer system knew whento expect a transmission. For example, when information or data werebeing wirelessly transmitted to the portable computer system, it wasusually in response to a request initiated by the portable computersystem. Thus, the portable computer system was deliberately placed in areceiving mode when a transmission was anticipated, and usually was notin a receiving mode otherwise.

The sophistication of portable computer systems has increased, andtherefore portable computer systems are frequently used in applicationsin which they need to be ready to receive transmitted information at anytime, similar to the way a cellular telephone operates. For example,when a cellular telephone is powered on, it is ready to receive anincoming call at any time. Similarly, a portable computer system isready to receive information at any time that the transceiver is poweredon, even if other parts of the portable computer system are in a sleep(low power) mode. Generally, devices transmitting information to theportable computer system have the expectation that the portable computersystem will be in a mode in which it can receive the information.

Accordingly, it is desirable for the portable computer system (with awireless transceiver) to remain “in coverage” when the transceiver ison; that is, it should have a persistent wireless connection to thenetwork. However, due to its portability, there may be occasions inwhich the portable computer system is moved “out of coverage.” Forinstance, while in one location, the portable computer system may haveestablished a wireless connection over a particular broadcast channelused by the network. After moving to a different location, a signal overthat channel may be too weak, and consequently the connection over thatchannel may be lost.

Currently, when the transceiver is on and the portable computer systemmoves out of coverage, the portable computer system will attempt tore-establish a wireless connection to the network over a differentchannel. Often, as described above, the portable computer system may bein a low power mode. Consequently, in order to re-establish connectionwith the network, the main processor needs to awaken from the low powermode. The main processor then implements a routine to scan for availablechannels, to select a channel, and to establish a connection over theselected channel.

However, waking up the main processor is problematic because it canconsume a significant amount of power, which is inconsistent with thedesire to reduce power consumption and conserve the life of the battery.Accordingly, what is needed is a method and/or system that can be usedfor re-establishing a wireless connection when an existing connection islost and that can reduce the amount of power needed to do so. Thepresent invention provides a novel solution to these needs.

SUMMARY OF THE INVENTION

The present invention provides a method and system that can be used forre-establishing a wireless connection when an existing connection islost while reducing the amount of power needed to do so. The presentinvention provides these advantages and others not specificallymentioned above but described in the sections to follow.

The present invention pertains to a method and system for establishing awireless connection between a portable computer system and a wirelessnetwork. In one embodiment, the wireless network is a Mobitex wirelesscommunication system. The present invention can be implemented when theportable computer system goes out of coverage and a wireless connectionneeds to be re-established The present invention can also be implementedwhen the portable computer system is powered on (at startup) and abroadcast channel cannot be acquired.

In one embodiment of the present invention, the portable computer systemhas a main processor and a digital signal processor (DSP). The mainprocessor is placed in a low power mode, conserving battery power. Whenan established wireless connection between the portable computer systemand the wireless network is lost (e.g., when the portable computersystem goes “out of coverage”), broadcast channels used by the wirelessnetwork are scanned under direction of the DSP instead of the mainprocessor. From the scan, the DSP can identify channels that have signalstrength sufficient for re-establishing the wireless connection. Thus,the main processor remains in the low power mode while the DSPimplements a search for an acceptable channel.

When the DSP identifies one or more acceptable channels, it wakes up themain processor and identifies to the main processor the channels havingsufficient signal strength. The main processor then establishes awireless connection using one of the channels identified by the DSP.When the DSP cannot find an acceptable channel, it repeats the search atperiodic intervals until an acceptable channel is identified.

In one embodiment, the DSP compares the signal strength of each channelto a threshold value in order to compile a list of those channels with asignal strength that is acceptable for a wireless connection. In anotherembodiment, when multiple acceptable channels are identified by the DSP,the DSP sorts (ranks) the channels according to their respective signalstrength. In either embodiment, the main processor is then awakened andestablishes a wireless connection with the wireless network, typicallyusing the channel with the highest signal strength.

In one embodiment, certain channels used by the wireless network aredisregarded by the DSP. For example, certain channels may not bescanned, or signals received over those channels may be ignored. Thus,channels known to have a lot of noise, or channels that are not suitablefor a wireless connection for some other reason, will not cause theprocessor to be unnecessarily awakened.

Thus, in accordance with the present invention, the DSP implements aprocess for performing multi-channel scans without waking the mainprocessor. Therefore, only the DSP needs to stay up to direct the scans.Not until the DSP determines that the portable computer system can beplaced into coverage, or the user tries to perform an over-the-airoperation manually, is the main processor awakened. This stops the deepsleep process and returns control to the protocol stack in the mainprocessor. The main processor can then establish the wireless connectionand place the portable computer system back into the in-coverage mode ofoperation. With the main processor remaining in a low power mode whilethe DSP performs the multi-channel scan, power is conserved and batterylife is prolonged (that is, batteries do not have to changed or chargedas frequently).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

FIG. 1 is a block diagram of an exemplary network environment includinga portable computer system in accordance with one embodiment of thepresent invention.

FIG. 2 is a top side perspective view of a portable computer system inaccordance with one embodiment of the present invention.

FIG. 3 is a bottom side perspective view of the portable computer systemof FIG. 2.

FIG. 4 is a block diagram of an exemplary portable computer system uponwhich embodiments of the present invention may be practiced.

FIG. 5 is a flowchart showing the steps in a process for establishing awireless connection between a portable computer system and a wirelessnetwork in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be recognizedby one skilled in the art that the present invention may be practicedwithout these specific details or with equivalents thereof. In otherinstances, well known methods, procedures, components, and circuits havenot been described in detail as not to unnecessarily obscure aspects ofthe present invention.

Notation and Nomenclature

Some portions of the detailed descriptions, which follow, are presentedin terms of procedures, steps, logic blocks, processing, and othersymbolic representations of operations on data bits that can beperformed on computer memory. These descriptions and representations arethe means used by those skilled in the data processing arts to mosteffectively convey the substance of their work to others skilled in theart. A procedure, computer executed step, logic block, process, etc., ishere, and generally, conceived to be a self-consistent sequence of stepsor instructions leading to a desired result. The steps are thoserequiring physical manipulations of physical quantities. Usually, thoughnot necessarily, these quantities take the form of electrical ormagnetic signals capable of being stored, transferred, combined,compared, and otherwise manipulated in a computer system. It has provenconvenient at times, principally for reasons of common usage, to referto these signals as bits, values, elements, symbols, characters, terms,numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the followingdiscussions, it is appreciated that throughout the present invention,discussions utilizing terms such as “scanning” or “determining” or“waking” or “identifying” or “comparing” or “sorting” or “selecting” or“establishing” or “disregarding” or “initiating” or the like, refer tothe action and processes of a computer system (e.g., process 500 of FIG.5), or similar electronic computing device, that manipulates andtransforms data represented as physical (electronic) quantities withinthe computer system's registers and memories into other data similarlyrepresented as physical quantities within the computer system memoriesor registers or other such information storage, transmission or displaydevices.

Exemplary Palmtop Platform

FIG. 1 is a block diagram of an exemplary network environment 50including a portable computer system 100 in accordance with oneembodiment of the present invention. Portable computer system 100 isalso known as a palmtop or palm-sized computer system, a hand-helddevice, a personal digital assistant (PDA), or a personal informationdevice (PID). In one embodiment, portable computer system 100 has theability to transmit and receive data and information over a wirelesscommunication interface (e.g., a radio interface).

In the present embodiment, base station 32 is both a transmitter andreceiver base station, which can be implemented by coupling it into anexisting public telephone network 34. Implemented in this manner, basestation 32 enables portable computer system 100 to communicate with aproxy server computer system 36, which is coupled by wire to theexisting public telephone network 34.

Furthermore, proxy server computer system 36 is coupled to the Internet52, thereby enabling portable computer system 100 to communicate withthe Internet 52. Coupled with Internet 52 are multiple computer systems(e.g., servers) exemplified by computer system 30. When communicatingwith a Web site over Internet 52, protocols such as CTP (CompactTransport Protocol) and CML (Compact Markup Language) can be used byportable computer system 100 in the present embodiment.

It should be appreciated that within the present embodiment, one of thefunctions of proxy server 36 is to perform operations over the Internet52 on behalf of portable computer system 100. For example, proxy server36 has a particular Internet address and acts as a proxy device forportable computer system 100 over the Internet 52.

It should be further appreciated that other embodiments of acommunications network, planned or envisioned, may be utilized inaccordance with the present invention. For example, a wirelessconnection may be made from portable computer system 100 either directlyto the Internet 52 or directly to computer system 30. It is alsoappreciated that portable computer system 100 may be coupled to computersystem networks other than the Internet 52, such as an Intranet, localarea network, or the like.

The data and information that are communicated between base station 32and portable computer system 100 are the same type of information anddata that can conventionally be transferred and received over a wirelesscommunication interface. It should be appreciated that one embodiment ofa wireless communication system in accordance with the present inventionis the Mobitex wireless communication system.

FIG. 2 is a perspective illustration of the top face 100 a of oneembodiment of the portable computer system 100 of the present invention.The top face 100 a contains a display screen 105 surrounded by a bezelor cover. A removable stylus 80 is also shown. The display screen 105 isa touch screen able to register contact between the screen and the tipof the stylus 80. The stylus 80 can be of any material to make contactwith the screen 105. The top face 100 a also contains one or morededicated and/or programmable buttons 75 for selecting information andcausing the computer system to implement functions. The on/off button 95is also shown.

FIG. 2 also illustrates a handwriting recognition pad or “digitizer”containing two regions 106 a and 106 b. Region 106 a is for the drawingof alphabetic characters therein (and not for numeric characters) forautomatic recognition, and region 106 b is for the drawing of numericcharacters therein (and not for alphabetic characters) for automaticrecognition. The stylus 80 is used for stroking a character within oneof the regions 106 a and 106 b. The stroke information is then fed to aninternal processor for automatic character recognition. Once charactersare recognized, they are typically displayed on the screen 105 forverification and/or modification.

FIG. 3 illustrates the bottom side 100 b of one embodiment of thepalmtop computer system that can be used in accordance with variousembodiments of the present invention. An extendible antenna 85 is shown,and also a battery storage compartment door 90 is shown. A serial port180 and an infrared port 64 are also shown. In one embodiment, infraredcommunication mechanism 64 is compliant with the IrDA (Infrared DataAssociation) standard and protocol.

FIG. 4 is a block diagram of one embodiment of a portable computersystem 100 upon which embodiments of the present invention may beimplemented. Portable computer system 100 is also often referred to as aPDA, a PID, a palmtop, or a hand-held computer system.

Portable computer system 100 includes an address/data bus 300 forcommunicating information, a central (main) processor 450 coupled withthe bus 300 for processing information and instructions, a volatilememory 410 (e.g., random access memory, RAM) coupled with the bus 300for storing information and instructions for the main processor 450, anda non-volatile memory 430 (e.g., read only memory, ROM) coupled with thebus 300 for storing static information and instructions for the mainprocessor 450. Portable computer system 100 also includes an optionaldata storage device 490 (e.g., a memory stick) coupled with the bus 300for storing information and instructions. Device 490 can be removable.Portable computer system 100 also contains a display device 105 coupledto the bus 300 for displaying information to the computer user.

In the present embodiment, portable computer system 100 includes atransceiver 408 providing it with the capability for wirelesscommunication. The transceiver 408 provides a wireless radio frequency(RF) communication link between computer system 100 and other devices,using any of the various RF protocols and standards. In one embodiment,the Mobitex wireless communication specification is used. It isappreciated that transceiver 408 may be integrated into portablecomputer system 100, or that transceiver 408 may be a separate componentcoupled to portable computer system using, for example, serial port 180.

It is appreciated that in another embodiment portable computer system100 may also include a telephony chipset or the like providing it withthe functionality of a cellular phone, in particular the capability totransmit and receive cellular communications. In one embodiment, thetelephony chipset is compatible with the standards for GSM and GPRS(Global System for Mobile Communications and General Packet RadioService, respectively). It is appreciated that other telephony protocolsand standards may also be used with the present invention.

In the present embodiment, portable computer system 100 of FIG. 4includes communication circuitry 420 coupled to bus 300. In oneembodiment, communication circuitry 420 is a universal asynchronousreceiver-transmitter (UART) module that provides the receiving andtransmitting circuits required for serial communication for both theserial port 180 and the infrared port 64. Communication circuitry 420also includes digital signal processor (DSP) 422 for processing data tobe transmitted or data that are received via transceiver 408.

Also included in computer system 100 is an optional alphanumeric inputdevice 106 that, in one implementation, is a handwriting recognition pad(“digitizer”). Alphanumeric input device 106 can communicate informationand command selections to main processor 450 via bus 300. In oneimplementation, alphanumeric input device 106 is a touch screen device.Alphanumeric input device 460 is capable of registering a position wherea stylus element (not shown) makes contact.

Portable computer system 100 also includes an optional cursor control ordirecting device (on-screen cursor control 480) coupled to bus 300 forcommunicating user input information and command selections to mainprocessor 450. In one implementation, on-screen cursor control device480 is a touch screen device incorporated with display device 105.On-screen cursor control device 480 is capable of registering a positionon display device 105 where a stylus element makes contact. The displaydevice 105 utilized with portable computer system 100 may be a liquidcrystal display (LCD) device, a cathode ray tube (CRT), a field emissiondisplay device (also called a flat panel CRT), or other display devicesuitable for generating graphic images and alphanumeric charactersrecognizable to the user. In the preferred embodiment, display device105 is a flat panel display.

DSP Control of Multi-Channel Scan for Re-Establishing Connections

FIG. 5 is a flowchart of the steps in a process 500 for establishing awireless connection between portable computer system 100 (FIG. 4) and awireless network 50 (FIG. 1) in accordance with one embodiment of thepresent invention. In the present embodiment, process 500 is implementedas computer-readable program instructions executed by portable computersystem 100. Significantly, to conserve power, aspects of process 500 areperformed by DSP 422 (FIG. 4) while main processor 450 is in a sleepmode, as will be seen.

In step 505 of FIG. 5, with reference also to FIG. 4, the main processor450 enters a low power mode (e.g., a sleep mode or deep sleep mode) in aconventional manner. In accordance with the present invention, mainprocessor 450 remains in the sleep mode through step 530 of process 500.

In step 510 of FIG. 5, with reference also to FIG. 4, the method andsystem of the present invention is automatically initiated based on atriggering event. In essence, a triggering event is an indication thatportable computer system 100 is out of coverage. In one embodiment, theout of coverage event is defined by the Mobitex specification. In thisembodiment, an out of coverage event occurs when portable computersystem 100 is unable to acquire a broadcast channel when portablecomputer system 100 is powered on (at startup). An out of coverage eventcan also be triggered when portable computer system 100 transmitsinformation to base station 32 (FIG. 1A) and does not receive anacknowledgment signal in return. Also, an out of coverage event canoccur when portable computer system 100 does not receive a transmissionfrom network 50 (FIG. 1A) for a specified period of time. It isappreciated that there may be other types of triggering events. It isalso appreciated that a user of portable computer system 100 maymanually initiate process 500.

In step 515 of FIG. 5, again with also reference to FIG. 4, DSP 422receives a command to begin the process of multi-channel scans. Thecommand can be received from, for example, the operating system orprotocol stack of portable computer system 100. The purpose of themulti-channel scan is to allow DSP 422 to identify those broadcastchannels that are strong enough to be used for a wireless connection. Aswill be seen, DSP 422 compiles the channels that can be used for thewireless connection into a list that is subsequently forwarded to mainprocessor 450.

Thus, in accordance with the present invention, DSP 422, not mainprocessor 450, directs the process of scanning the broadcast channelsused by the wireless communication network (e.g., network 50 of FIG. 2),without the involvement of the protocol stack. Therefore, main processor450 can remain in the sleep mode, and only DSP 422 needs to stay up todirect the scans. As a result, less power is consumed, increasingbattery life and reducing the frequency at which batteries need to bereplaced or recharged.

The channels used by the wireless communication network are known; inone embodiment, the channels are specified by the Mobitex specification.In the present embodiment, DSP 422 directs the scanning of all channels.However, in one embodiment, DSP 422 ignores certain channels during thescan. For example, interfering sources can add energy (e.g., noise) tocertain channels; these channels are known and therefore can beidentified to DSP 422 in advance of the scan. DSP 422 may then skipthese channels during the scan, or DSP 422 may disregard these channelsin the process of identifying channels strong enough to be used for thewireless connection. Thus, DSP 422 is prevented from incorrectlydeducing that a proper signal is being received over those channels whenin fact only noise or other interference is being received.

In step 520 of FIG. 5, DSP 422 of FIG. 4 determines which broadcastchannels will be acceptable for the wireless connection. In oneembodiment, DSP 422 accomplishes this by comparing a measure of signalstrength to a threshold value. In one embodiment, the measure of signalstrength is the RF energy or RSSI (receiver signal strength indicator)of the signal received over a channel. In this embodiment, DSP 422compares the RF energy or RSSI to the threshold value. If the measure ofsignal strength is equal to or greater than the threshold value, thenthe channel is an acceptable candidate and may be used for the wirelessconnection. If the measure of signal strength is less than the thresholdvalue, than the channel is not an acceptable candidate. It isappreciated that other measures of signal strength and methods otherthan comparing to a threshold value may be used to identify acceptablebroadcast channels in accordance with the present invention.

In step 525 of FIG. 5, if no acceptable broadcast channels are found,process 500 returns to step 515. In this case, after a predefinedinterval of time has passed, DSP 422 (FIG. 4) repeats steps 515 and 520until an acceptable channel is found. In one embodiment, DSP 422 alsoenters into a sleep mode during the interval of time before steps 515and 520 are repeated.

Step 530 of FIG. 5 addresses the case in which DSP 422 (FIG. 4) hasfound at least one acceptable channel. When more than one channel hasbeen found, DSP 422 compiles a list of acceptable channels. In oneembodiment, DSP 422 sorts the list of channels according to eachchannel's relative signal strength, based on the measure of signalstrength determined in step 520 above.

In step 535 of FIG. 5, with reference also to FIG. 4, DSP 422 wakes upmain processor 450 and provides to main processor 450 the list ofbroadcast channels that can be used to establish a wireless connection.Thus, in accordance with the present invention, main processor 450remains in the sleep mode until DSP 422 finds at least one acceptablebroadcast channel. In other words, main processor 450 is not awakeneduntil preparations for a wireless connection are complete, therebyconserving power and extending battery life.

In step 540 of FIG. 5, main processor 450 (FIG. 4) establishes thewireless connection to the wireless network (e.g., network 50 of FIG. 2)using known protocols, such as those described by the Mobitexspecification. In one embodiment, main processor 450 uses the broadcastchannel having the highest measure of signal strength as determined instep 520 above. Subsequently, main processor 450 can then return to thesleep mode, and portable computer system 100 enters the in-coverage modein which it periodically checks for transmissions over the wirelessconnection now established.

In summary, the present invention provides a method and system thatreduce the power needed for establishing a wireless connection when anexisting connection is lost or when a broadcast channel cannot beacquired. In accordance with the present invention, the DSP implements aprocess for performing multi-channel scans without waking the mainprocessor. Therefore, only the DSP needs to stay up to direct the scans.Not until the DSP determines that the portable computer system can beplaced into coverage, or the user tries to perform an over-the-airoperation manually, is the main processor awakened. This stops the deepsleep process and returns control to the protocol stack in the mainprocessor. The main processor can then establish the wireless connectionand place the portable computer system back into the in-coverage mode ofoperation. With the main processor remaining in a low power mode whilethe DSP performs the multi-channel scan, power is conserved, prolongingthe battery life of the portable computer system (that is, batteries donot have to changed or charged as frequently).

The present invention has been described in the context of a portablecomputer system; however, the present invention may also be implementedin other types of devices having, for example, a main processor and aDSP, such that the main processor is placed in or remains in a low powermode while the DSP performs certain functions on behalf of theprocessor. Furthermore, it is appreciated that these certain functionsmay include functions other than those associated with establishing (orre-establishing) wireless connections.

The preferred embodiment of the present invention, direct DSP control ofmulti-channel scan for re-establishing connections in a wirelesslynetworked device, is thus described. While the present invention hasbeen described in particular embodiments, it should be appreciated thatthe present invention should not be construed as limited by suchembodiments, but rather construed according to the below claims.

What is claimed is:
 1. In a computer system comprising a first processorand a second processor, a method for establishing a wireless connectionbetween said computer system and a wireless network, said methodcomprising: during a scan interval, (a) scanning a plurality ofbroadcast channels used by said wireless network, wherein said scanningis performed under direction of said second processor while said firstprocessor is in a reduced power mode, (b) making a determination as towhich of said plurality of broadcast channels are acceptable for saidwireless connection, wherein making said determination is performed bysaid second processor while said first processor remains in said reducedpower mode, (c) generating information about a plurality of acceptablebroadcast channels, and (d) providing said information to said firstprocessor; in response to said first processor receiving saidinformation, waking up said first processor; and establishing saidwireless connection using one of said plurality of acceptable broadcastchannels.
 2. The method of claim 1, wherein making said determinationcomprises comparing a signal strength of a signal received over each ofsaid plurality of broadcast channels to a signal strength threshold,wherein said signal strength threshold defines a minimum signal strengththat is acceptable for said wireless connection.
 3. The method of claim2, further comprising: sorting said plurality of acceptable broadcastchannels according to said signal strength associated with each of saidplurality of acceptable broadcast channels.
 4. The method of claim 3,further comprising: selecting, from said plurality of acceptablebroadcast channels, a broadcast channel having a highest signalstrength; and wherein establishing said wireless connection includesusing said selected broadcast channel, wherein said establishing isperformed under direction of said first processor.
 5. The method ofclaim 1, wherein said scanning comprises disregarding certain broadcastchannels used by said wireless network.
 6. The method of claim 1,wherein said second processor network is a digital signal processor. 7.The method of claim 1, wherein said information about said plurality ofacceptable broadcast channels comprises a list of said plurality ofacceptable broadcast channels.
 8. The method of claim 1, wherein saidscanning is automatically initiated when a previously establishedwireless connection between said computer system and said wirelessnetwork is lost.
 9. The method of claim 1, wherein said scanning isautomatically initiated when said computer system is powered on and anacceptable broadcast channel for said wireless connection is notacquired.
 10. A computer system comprising: a wireless transceiver; afirst processor coupled to said transceiver; and a second processorcoupled to said first processor, said second processor operable forperforming a method for establishing a wireless connection between saidcomputer system and a wireless network, said method comprising: during ascan interval, (a) scanning a plurality of broadcast channels used bysaid wireless network, wherein said scanning is performed while saidfirst processor is in a reduced power mode, (b) making a determinationas to which of said plurality of broadcast channels are acceptable forsaid wireless connection, wherein making said determination is executedwhile said first processor remains in said reduced power mode, (c)generating information about a plurality of acceptable broadcastchannels, and (d) providing said information to said first processor;wherein providing said information to said first processor causes saidfirst processor to wake up from said reduced power mode.
 11. Thecomputer system of claim 10, wherein making said determination comprisescomparing a signal strength of a signal received over each of saidplurality of broadcast channels to a signal strength threshold, whereinsaid signal strength threshold defines a minimum signal strength that isacceptable for said wireless connection.
 12. The computer system ofclaim 11, wherein said method further comprises: sorting said pluralityof acceptable broadcast channels according to said signal strengthassociated with each of said plurality of acceptable broadcast channels.13. The computer system of claim 12, wherein said first processorselects a broadcast channel having a highest signal strength from saidplurality of acceptable broadcast channels and establishes said wirelessconnection using said selected broadcast channel.
 14. The computersystem of claim 10, wherein said scanning comprises disregarding certainbroadcast channels used by said wireless network.
 15. The computersystem of claim 10, wherein said second processor is a digital signalprocessor.
 16. The computer system of claim 10, wherein said informationabout said plurality of acceptable broadcast channels comprises a listof said plurality of acceptable broadcast channels.
 17. The computersystem of claim 10, wherein said scanning is automatically initiatedwhen a previously established wireless connection between said computersystem and said wireless network is lost.
 18. The computer system ofclaim 10, wherein said scanning is automatically initiated when saidcomputer system is powered on and an acceptable broadcast channel forsaid wireless connection is not acquired.
 19. In a computer systemcomprising a first processor and a second processor, a method forestablishing a wireless connection between said computer system and awireless network, said method comprising: during a scan interval, (a)scanning a plurality of broadcast channels used by said wirelessnetwork, wherein said scanning is performed under direction of saidsecond processor while said first processor is in a reduced power modeand wherein said scanning is automatically initiated in response to atriggering event, (b) comparing, by said second processor, a signalstrength of a signal received over each of said plurality of broadcastchannels to a signal strength threshold, wherein said signal strengththreshold defines an acceptable signal strength for said wirelessconnection, (c) generating information about a plurality of acceptablebroadcast channels based on said comparison, and (d) providing saidinformation to said first processor; in response to said first processorreceiving said information, waking up said first processor; andestablishing said wireless connection using one of said plurality ofacceptable broadcast channels.
 20. The method of claim 19, furthercomprising: sorting said plurality of acceptable broadcast channelsaccording to said signal strength associated with each of said pluralityof acceptable broadcast channels.
 21. The method of claim 20, furthercomprising: selecting, from said plurality of acceptable broadcastchannels, a broadcast channel having a highest signal strength; andwherein establishing said wireless connection includes using saidselected broadcast channel.
 22. The method of claim 19, wherein saidscanning comprises disregarding certain broadcast channels used by saidwireless network.
 23. The method of claim 19, wherein said secondprocessor is a digital signal processor.
 24. The method of claim 19,wherein said triggering event is a loss of a previously establishedwireless connection between said computer system and said wirelessnetwork.
 25. The method of claim 19, wherein said triggering event is alack of acquisition of a broadcast channel for said wireless connectionwhen said computer system is powered on.